The advent of genomic, transcriptomic and proteomic-based approaches has revolutionised our abili... more The advent of genomic, transcriptomic and proteomic-based approaches has revolutionised our ability to describe marine microbial communities, including biogeography, metabolic potential and diversity, mechanisms of adaptation, and phylogeny and evolutionary history. New inter-disciplinary approaches are needed to move from this descriptive level to improved quantitative, process-level understanding of the roles of marine microbes in biogeochemical cycles, and of the impact of environmental change on the marine microbial ecosystem. To link studies at levels from the genome to the organism, to ecological strategies and organism and ecosystem response, requires new modelling approaches. Key to this will be a fundamental shift in modelling scale that represents microorganisms from the level of their macromolecular components. This will enable contact with omics datasets, and allow acclimation and adaptive response at the phenotype level (i.e. traits) to be simulated as a combination of ...
Current climate engineering proposals do not come close to addressing the complex and contested n... more Current climate engineering proposals do not come close to addressing the complex and contested nature of conceivable 'climate emergencies' resulting from unabated greenhouse-gas emissions.
Continuing business-as-usual with regards to greenhouse-gas emissions will increase the likelihood of 'dangerous' climate changes. In response to this risk, Crutzen argued in 2006 that a 5 °C warmer world will probably have catastrophic consequences and that the only way out may be to engineer the Earth's climate by injecting aerosols into the stratosphere. The possibility of a future 'climate emergency' has subsequently been used to justify research on climate engineering — the deliberate modification of the Earth's climate. Over time, the emergency framing has evolved to become a central argument for why we should consider investigating solar radiation management (SRM) techniques, which reduce the amount of sunlight absorbed at the Earth's surface. But whether SRM can possibly prevent or counteract a climate emergency raises the more fundamental question of what a climate emergency actually is.
Proceedings of the National Academy of Sciences of the United States of America, Jan 24, 2014
A shift toward higher atmospheric oxygen concentration during the late Proterozoic has been infer... more A shift toward higher atmospheric oxygen concentration during the late Proterozoic has been inferred from multiple indirect proxies and is seen by many as a prerequisite for the emergence of complex animal life. However, the mechanisms controlling the level of oxygen throughout the Proterozoic and its eventual rise remain uncertain. Here we use a simple biogeochemical model to show that the balance between long-term carbon removal fluxes via terrestrial silicate weathering and ocean crust alteration plays a key role in determining atmospheric oxygen concentration. This balance may be shifted by changes in terrestrial weatherability or in the generation rate of oceanic crust. As a result, the terrestrial chemical weathering flux may be permanently altered--contrasting with the conventional view that the global silicate weathering flux must adjust to equal the volcanic CO2 degassing flux. Changes in chemical weathering flux in turn alter the long-term supply of phosphorus to the ocean...
The Atlantic Meridional Overturning Circulation (AMOC) exhibits two stable states in models of va... more The Atlantic Meridional Overturning Circulation (AMOC) exhibits two stable states in models of varying complexity. Shifts between alternative AMOC states are thought to have played a role in past abrupt climate changes, but the proximity of the climate system to a threshold for future AMOC collapse is unknown. Generic early warning signals of critical slowing down before AMOC collapse have been found in climate models of low and intermediate complexity. Here we show that early warning signals of AMOC collapse are present in a fully coupled atmosphere-ocean general circulation model, subject to a freshwater hosing experiment. The statistical significance of signals of increasing lag-1 autocorrelation and variance vary with latitude. They give up to 250 years warning before AMOC collapse, after ~550 years of monitoring. Future work is needed to clarify suggested dynamical mechanisms driving critical slowing down as the AMOC collapse is approached.
The Late Ordovician period, ending 444 million years ago, was marked by the onset of glaciations.... more The Late Ordovician period, ending 444 million years ago, was marked by the onset of glaciations. The expansion of non-vascular land plants accelerated chemical weathering and may have drawn down enough atmospheric carbon dioxide to trigger the growth of ice sheets.
... Climate change mitigation: trade-offs between delay and strength of action required Naomi E. ... more ... Climate change mitigation: trade-offs between delay and strength of action required Naomi E. Vaughan·Timothy M. Lenton· John G. Shepherd ... 1996; Matthews 2006). Alternatively, forward modelling can be under-taken until a stabilising profile is achieved. ...
The advent of genomic, transcriptomic and proteomic-based approaches has revolutionised our abili... more The advent of genomic, transcriptomic and proteomic-based approaches has revolutionised our ability to describe marine microbial communities, including biogeography, metabolic potential and diversity, mechanisms of adaptation, and phylogeny and evolutionary history. New inter-disciplinary approaches are needed to move from this descriptive level to improved quantitative, process-level understanding of the roles of marine microbes in biogeochemical cycles, and of the impact of environmental change on the marine microbial ecosystem. To link studies at levels from the genome to the organism, to ecological strategies and organism and ecosystem response, requires new modelling approaches. Key to this will be a fundamental shift in modelling scale that represents microorganisms from the level of their macromolecular components. This will enable contact with omics datasets, and allow acclimation and adaptive response at the phenotype level (i.e. traits) to be simulated as a combination of ...
Current climate engineering proposals do not come close to addressing the complex and contested n... more Current climate engineering proposals do not come close to addressing the complex and contested nature of conceivable 'climate emergencies' resulting from unabated greenhouse-gas emissions.
Continuing business-as-usual with regards to greenhouse-gas emissions will increase the likelihood of 'dangerous' climate changes. In response to this risk, Crutzen argued in 2006 that a 5 °C warmer world will probably have catastrophic consequences and that the only way out may be to engineer the Earth's climate by injecting aerosols into the stratosphere. The possibility of a future 'climate emergency' has subsequently been used to justify research on climate engineering — the deliberate modification of the Earth's climate. Over time, the emergency framing has evolved to become a central argument for why we should consider investigating solar radiation management (SRM) techniques, which reduce the amount of sunlight absorbed at the Earth's surface. But whether SRM can possibly prevent or counteract a climate emergency raises the more fundamental question of what a climate emergency actually is.
Proceedings of the National Academy of Sciences of the United States of America, Jan 24, 2014
A shift toward higher atmospheric oxygen concentration during the late Proterozoic has been infer... more A shift toward higher atmospheric oxygen concentration during the late Proterozoic has been inferred from multiple indirect proxies and is seen by many as a prerequisite for the emergence of complex animal life. However, the mechanisms controlling the level of oxygen throughout the Proterozoic and its eventual rise remain uncertain. Here we use a simple biogeochemical model to show that the balance between long-term carbon removal fluxes via terrestrial silicate weathering and ocean crust alteration plays a key role in determining atmospheric oxygen concentration. This balance may be shifted by changes in terrestrial weatherability or in the generation rate of oceanic crust. As a result, the terrestrial chemical weathering flux may be permanently altered--contrasting with the conventional view that the global silicate weathering flux must adjust to equal the volcanic CO2 degassing flux. Changes in chemical weathering flux in turn alter the long-term supply of phosphorus to the ocean...
The Atlantic Meridional Overturning Circulation (AMOC) exhibits two stable states in models of va... more The Atlantic Meridional Overturning Circulation (AMOC) exhibits two stable states in models of varying complexity. Shifts between alternative AMOC states are thought to have played a role in past abrupt climate changes, but the proximity of the climate system to a threshold for future AMOC collapse is unknown. Generic early warning signals of critical slowing down before AMOC collapse have been found in climate models of low and intermediate complexity. Here we show that early warning signals of AMOC collapse are present in a fully coupled atmosphere-ocean general circulation model, subject to a freshwater hosing experiment. The statistical significance of signals of increasing lag-1 autocorrelation and variance vary with latitude. They give up to 250 years warning before AMOC collapse, after ~550 years of monitoring. Future work is needed to clarify suggested dynamical mechanisms driving critical slowing down as the AMOC collapse is approached.
The Late Ordovician period, ending 444 million years ago, was marked by the onset of glaciations.... more The Late Ordovician period, ending 444 million years ago, was marked by the onset of glaciations. The expansion of non-vascular land plants accelerated chemical weathering and may have drawn down enough atmospheric carbon dioxide to trigger the growth of ice sheets.
... Climate change mitigation: trade-offs between delay and strength of action required Naomi E. ... more ... Climate change mitigation: trade-offs between delay and strength of action required Naomi E. Vaughan·Timothy M. Lenton· John G. Shepherd ... 1996; Matthews 2006). Alternatively, forward modelling can be under-taken until a stabilising profile is achieved. ...
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Papers by Timothy Lenton
Continuing business-as-usual with regards to greenhouse-gas emissions will increase the likelihood of 'dangerous' climate changes. In response to this risk, Crutzen argued in 2006 that a 5 °C warmer world will probably have catastrophic consequences and that the only way out may be to engineer the Earth's climate by injecting aerosols into the stratosphere. The possibility of a future 'climate emergency' has subsequently been used to justify research on climate engineering — the deliberate modification of the Earth's climate. Over time, the emergency framing has evolved to become a central argument for why we should consider investigating solar radiation management (SRM) techniques, which reduce the amount of sunlight absorbed at the Earth's surface. But whether SRM can possibly prevent or counteract a climate emergency raises the more fundamental question of what a climate emergency actually is.
Continuing business-as-usual with regards to greenhouse-gas emissions will increase the likelihood of 'dangerous' climate changes. In response to this risk, Crutzen argued in 2006 that a 5 °C warmer world will probably have catastrophic consequences and that the only way out may be to engineer the Earth's climate by injecting aerosols into the stratosphere. The possibility of a future 'climate emergency' has subsequently been used to justify research on climate engineering — the deliberate modification of the Earth's climate. Over time, the emergency framing has evolved to become a central argument for why we should consider investigating solar radiation management (SRM) techniques, which reduce the amount of sunlight absorbed at the Earth's surface. But whether SRM can possibly prevent or counteract a climate emergency raises the more fundamental question of what a climate emergency actually is.